RAID data storage system having keyed SAS expansion cables

Abstract

A data storage system has a first and second chassis. Each of tow datapaths has a keyed front end datapath point connected to a keyed expansion point of a respective SAS expander of the first chassis, and has a keyed backend datapath point connected to a keyed front end expansion point of a respective SAS expander of the second chassis.

1. A data storage system, comprising:
 (A) a first chassis having therein:
 a first pair of SAS expanders including a first SAS expander and a second SAS expander, each one having: a bidirectional front end point, a plurality of bidirectional backend points, and a keyed expansion point; 
 
 (B) a second chassis having therein:
 a second pair of SAS expanders, including a third SAS expander and a fourth SAS expander each one of the pair of SAS expanders having a keyed bidirectional front end expansion point configured to receive only a correspondingly keyed backend datapath point and a keyed bidirectional backend expansion point configured to receive only a correspondingly keyed front end datapath point; 
 
 (C) a first datapath having a keyed front end datapath point connected to the keyed expansion point of a first SAS expander and a keyed backend datapath point connected to the keyed front end expansion point of the third SAS expander; and 
 (D) a second datapath having a keyed front end datapath point connected to the keyed expansion point of the second SAS expander and a keyed backend datapath point connected to the keyed front end expansion point of the fourth SAS expander.